usb: dwc3: drop EP0_STALL state

Whenever we issue a Set Stall command on EP0,
the state machine will be restarted and Stall
is cleared automatically, when core receives
the next SETUP packet.

There's no need to track that EP0_STALL state.
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/core.h

@@ -375,7 +375,6 @@ enum dwc3_ep0_state {
 	EP0_SETUP_PHASE,
 	EP0_DATA_PHASE,
 	EP0_STATUS_PHASE,
-	EP0_STALL,
 };
 
 enum dwc3_link_state {

drivers/usb/dwc3/ep0.c

@@ -68,8 +68,6 @@ static const char *dwc3_ep0_state_string(enum dwc3_ep0_state state)
 		return "Data Phase";
 	case EP0_STATUS_PHASE:
 		return "Status Phase";
-	case EP0_STALL:
-		return "Stall";
 	default:
 		return "UNKNOWN";
 	}

drivers/usb/dwc3/gadget.c

@@ -872,8 +872,14 @@ int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value)
 	memset(&params, 0x00, sizeof(params));
 
 	if (value) {
-		if (dep->number == 0 || dep->number == 1)
-			dwc->ep0state = EP0_STALL;
+		if (dep->number == 0 || dep->number == 1) {
+			/*
+			 * Whenever EP0 is stalled, we will restart
+			 * the state machine, thus moving back to
+			 * Setup Phase
+			 */
+			dwc->ep0state = EP0_SETUP_PHASE;
+		}
 
 		ret = dwc3_send_gadget_ep_cmd(dwc, dep->number,
 			DWC3_DEPCMD_SETSTALL, &params);